Head rest support

ABSTRACT

A headrest support that absorbs impact occurring on the headrest in the direction of its height is provided with a spring structure formed vertically downward from a lower side of a lock piece retaining hole, which prevents the clattering of a tube body relative to a receptacle tube. Resin-made springs are formed between cutout grooves extending in an outer peripheral surface of the tube body substantially parallel in the up-down direction, which are easily assembled by a lock piece, the tube body and a spring.

TECHNICAL FIELD

The invention relates to a headrest support and, more particularly, to aheadrest support that supports a headrest at an upper end of a seatback.

BACKGROUND ART

As this type of headrest support, a headrest support shown in FIG. 34 isconventionally known.

A headrest stay 1 is a rod-like body protruded from a bottom surface ofa headrest that is supported above a seatback. Wedge-shaped heightadjustment grooves 1 a are formed on a side surface of the headrest stay1.

A headrest support 2 has a tube body 3 that is formed into a tubularshape into which the headrest stay 1 can be inserted, and that isreceived and supported by a not-shown square pipe-made receptacle tubefixed by welding to a frame of the seatback, and a metal-made lock plate4 that is inserted into a portion of the tube body 3 that is closer toan upper end thereof in a direction perpendicular to the headrest stay1.

The lock plate 4 has a through-hole 4 a that is elongated so as not toimpede insertion of the headrest stay 1. An end of the lock plate 4 isprovided with a push-in operating portion 4 b that is integrally formedfrom resin.

The tube body 3 is provided with springs 5, 5 that contact the push-inoperating portion 4 b and urge the push-in operating portion 4 b in sucha manner as to push it out. In order to prevent the lock plate 4 fromfalling apart despite reaction forces from the springs, a stopper pin 6is inserted into the tube body 3 from above, extending in a directionperpendicular to the direction of insertion of the lock plate 4.

A slit 4 c for insertion of the stopper pin 6 is formed on the side ofthe lock plate 4. The stopper pin 6 and the slit 4 c restrict themovable range of the lock plate 4.

The movable range of the lock plate 4 has a positional relationship thatwhen the lock plate 4 is pushed in against the springs 5, 5, the lockplate 4 does not interfere, with the headrest stay 1, and that when thelock plate 4 is pushed out by the springs 5, 5, an edge portion of thethrough-hole 4 a slightly interferes with the headrest stay 1.

That is, during a normal stable state, the lock plate 4 is in apositional relationship that the lock plate 4 interferes with theheadrest stay 1, and thus engages with a height adjustment groove 1 a.When a push-in operation is performed by using the push-in operatingportion 4 b, the engagement is discontinued so that the headrest stay 1becomes movable up and down.

An outer peripheral surface of the tube body 3 is provided with agenerally rectangular tongue piece that is formed by forming a generallysquared U-shaped groove, and that has, at its distal end side, aprotrusion protruded outwards, and that has flexibility substantially ina direction of a diameter of the tube body 3. When the tube body 3 isplaced in the receptacle tube, the protrusion formed on the distal endside of the tongue piece is pressed against an inner peripheral surfaceof the receptacle tube so as to prevent the tube body from clatteringagainst the receptacle tube.

DISCLOSURE OF THE INVENTION

The above-described conventional headrest support has the followingproblems.

First, when the tube body is placed in the receptacle tube, an upper endsite of the tube body is pressed against an opening end portion of thereceptacle tube. Therefore, if an impact occurs on the headrest in adirection of a height, the impact cannot be absorbed.

Second, since the generally rectangular tongue piece formed in the outerperipheral surface of the tube body 3 is supported only at its lowerside by the tube body, the tongue piece cannot be provided with asufficient strength, and is poor in durability.

Third, during assembly of the headrest support, the headrest stay 1 mustbe inserted into the tube body 3 while the lock plate 4 is being pressedagainst the tube body 3. Thus, the assembly workability is not good.

The invention has been accomplished in view of the aforementionedproblems. It is an object of the invention to provide a headrest supportthat is capable of absorbing an impact occurring on the headrest in adirection of a height, and that has a sufficient strength and allows animprovement in assembly workability.

To achieve the aforementioned object, the invention has a constructionincluding: a tube body that is inserted into and supported by areceptacle tube disposed in a seatback, and that retains a headrest stayinserted therein, and that allows an adjustment of a height of theheadrest stay; and a spring structure that is protruded from a distalend side of the tube body toward an opening end portion of thereceptacle tube, and that urges the distal end side of the tube body tomove away from the opening end portion of the receptacle tube, and thaturges the distal end side of the tube body to move away from the openingend portion of the receptacle tube when the tube body is pushed down toa side; of the receptacle tube.

In the thus-constructed invention, the tube body is inserted in andsupported by the receptacle tube disposed in the seatback, and supportsthe headrest stay inserted therein, and adjusts the height of theheadrest stay.

When the tube body is pushed down to a side of the receptacle tube, thespring structure protruded from the distal end side of the tube bodytoward the opening end portion of the receptacle tube urges the distalend side of the tube body to move away from the opening end portion ofthe receptacle tube. Therefore, if impact occurs on the headrest in thedirection of its height, the impact is absorbed by the spring structure.

The tube body needs merely to be a tube body that is inserted into andsupported by the receptacle tube disposed in the seatback, and thatretains the headrest stay inserted therein, and that allows adjustmentof the height of the headrest stay. For example, the tube body may be atube body having a retaining hole capable of retaining the headrest staywhile orienting the headrest stay in a direction of an axis thereof, anda lock piece retaining hole that allows the lock piece to be insertedthereinto from a side opposite from the height adjustment groove, andthat allows the lock nail to be advanced and withdrawn in a direction ofinsertion.

The spring structure needs merely to be a spring structure that isprotruded from a distal end side of the tube body toward the opening endportion of the receptacle tube, and that urges the distal end side ofthe tube body to move away from the opening end portion of thereceptacle tube when the tube body is pushed down to a side of thereceptacle tube. The spring structure may be a resin spring formedintegrally with the tube body, or may be a spring structure that urges amember formed separately from the tube body by means of a spring or thelike, etc.

In the former case, the resin spring is not restricted in shape in aviewpoint that the resin spring needs merely to be able to urge thedistal end side of the tube body to move away from the opening endportion of the receptacle tube when the tube body is pushed down to theside of the receptacle tube. That is, the resins spring may be a resinspring that has a ring shape and is deformable in a predetermineddirection, or may be a resin spring that has an arm having a flexibilityin a predetermined direction, etc.

As an example of the construction in which an arm having a flexibilityas-mentioned above is provided, a first resin arm connecting a pluralityof positions facing the receptacle tube and a second resin arm extendingin a plurality of directions from a central portion of the first armtoward the opening end portion of the receptacle tube may be formed inthe tube body. In this example, if an impact occurs in the direction ofthe height, the impact can be absorbed by causing the first resin armand the second resin arm contacting the opening end portion to bend inthe direction of the height.

In this case, it is also possible to provide the spring structure withan additional function, such as, a function of restricting rotation ofthe tube body, or the like.

If, as an example of the construction in the aforementioned case, astopper nail is protruded from a central portion of the first resin armtoward the opening end portion of the receptacle tube, and a stoppergroove for restricting rotation of the tube body by engaging with thestopper nail is formed in the receptacle tube, rotation of the tube bodycan be restricted by the stopper groove receiving and engaging with thestopper nail.

Although the spring structure is provided for absorbing impact in thedirection of the height, the tube body may clatter against thereceptacle tube if impact occurs in a substantially horizontaldirection. Therefore, it is also possible to provide the tube body witha construction for preventing such clattering.

As an example of the construction in the aforementioned case, theinvention has a construction including: a tube body that is insertedinto and supported by a receptacle tube disposed in a seatback, and thatretains a headrest stay inserted therein, and that allows an adjustmentof a height of the headrest stay; and a resin-made spring including aflexible portion that is formed between cutout grooves extending in anouter peripheral surface of the tube body substantially parallel in adirection of an axis of the tube body, and that has a flexibilitysubstantially in a direction of a diameter of the tube body, andprotrusion that is protruded outwards from the flexible portion, andthat presses an inner peripheral surface of the receptacle tube whilebending the flexible portion inwards when the tube body is inserted inthe receptacle tube.

In the thus-constructed invention, the tube body is inserted in andsupported by the receptacle tube disposed in the seatback, and retainsthe headrest stay inserted therein, and adjusts the height of theheadrest stay.

When the tube body is inserted in the receptacle tube, the protrusionprotruded outwards from the flexible portion presses the innerperipheral surface of the receptacle tube while causing the flexibleportion that is formed between the cutout grooves extending in the outerperipheral surface of the tube body substantially parallel in thedirection of the axis of the tube body and that has a flexibilitysubstantially in the direction of the diameter of the tube body to bendinwards, thereby preventing the clattering of the tube body relative tothe receptacle tube.

The tube body needs merely to be a tube body that is inserted into andsupported by the receptacle tube, disposed in the seatback, and thatretains the headrest stay inserted therein, and that allows adjustmentof the height of the headrest stay. The tube body may be constructedsimilarly to the tube body in the invention in accordance with claim 1.

The resin-made spring needs merely to be a resin-made spring whichincludes a flexible portion that is formed between cutout groovesextending in an outer peripheral surface of the tube body substantiallyparallel in a direction of an axis of the tube body and that has aflexibility substantially in a direction of a diameter of the tube body,and a protrusion that is protruded outwards from the flexible portionand that presses an inner peripheral surface of the receptacle tubewhile bending the flexible portion inwards when the tube body isinserted in the receptacle tube, and is able to prevent the tube bodyfrom clattering relative to the receptacle tube when an impact occurs ina substantially horizontal direction.

Furthermore, it is possible to provide the resin-made spring with atapered shape that gradually becomes thinner toward the side of thereceptacle tube, so as to allow the tube body to be smoothly insertedinto the receptacle tube.

The resin-made spring needs merely to be a resin-made spring that isprovided on the outer peripheral surface of the tube body. Theresin-made spring may be a resin-made spring that is formed at a singlelocation, resin-made springs that are formed at a plurality oflocations, etc.

In the latter case, it is possible to form a resin-made spring from apredetermined location on the outer peripheral surface of the tube bodyand form another resin-made spring from an outer peripheral surfaceportion of the tube-body opposite from the aforementioned predeterminedlocation.

Thus, the resin-made springs press the inner peripheral surface of thereceptacle tube in opposite directions, so that clattering can-beeffectively prevented.

Furthermore, if a plurality of resin-made springs are formed, theresin-made springs may have equal heights or different heights.

In particular, if clattering caused by impact applied in the fore-aftdirection of the vehicle during braking or the like needs to beprevented, provision of the resin-made spring in the fore-aft directionof the vehicle will effectively prevents such clattering.

The tube body may also be constructed so as to allow an improvement inthe working efficiency of assembly of the headrest stay.

As an example of the construction the aforementioned case, the inventionhas a construction including: a lock piece having a lock nail disposedat a position that faces a height adjustment groove formed on a side;face of the headrest stay; a tube body having a retaining hole capableof retaining the headrest stay while orienting the headrest stay in adirection of an axis thereof, and a lock piece retaining hole thatallows the lock piece to be inserted thereinto from a side opposite fromthe height adjustment groove, and that allows the lock nail to beadvance and withdrawn in a direction of insertion; and engagementstructure that engages the lock piece and the tube body with each otherand restricts a movement of the lock nail from a position of lockingwith the height adjustment groove toward an opening of the lock pieceretaining hole; and a spring structure that presses the lock piecedisposed in the lock piece retaining hole from a side of the lock nailto the headrest stay.

In the thus-constructed invention, when the lock piece is inserted fromthe lock piece retaining hole formed in the tube body, the lock nail,disposed at a position facing the height adjustment groove, becomesadvanceable and withdrawable in the direction of insertion.

When the lock piece is engaged with the tube body by the engagementstructure formed between the lock piece and the tube body, the lock nailbecomes incapable of being moved from the position of locking with theheight adjustment groove formed on the side surface of the headrest staytoward the opening of the lock piece retaining hole.

Therefore, the lock piece will not fall apart from the lock pieceretaining hole even though the spring mechanism presses the lock piecefrom a deep inward side of the lock piece retaining hole toward theopening of the lock piece retaining hole.

Hence, when the headrest stay is to be inserted into the retaining holeafter the lock piece is inserted into the lock piece retaining holeduring an assembly process, it is not necessary to insert the headreststay into the retaining hole while pressing the lock piece against thelock piece retaining hole.

After assembly is completed in this manner, the spring mechanism pressesthe lock piece in the lock piece retaining hole against the headreststay from the side of the lock nail. Therefore, during a normal state,the lock nail is engaged with the height adjustment groove at the lockposition, thereby locking the height of the headrest stay.

If the lock piece is pushed toward a deep inward side of the lock pieceretaining hole, the lock nail is withdrawn from the height adjustmentgroove, so that it becomes possible to change the height of the headreststay.

Then, when the lock piece is released after the headrest stay isadjusted to a desired height, the lock piece is pushed back toward theopening side by the sprig mechanism, so that the lock piece engages withthe height adjustment groove again.

The headrest stay herein needs merely to be a headrest stay that has onits, side surface a height adjustment groove. The headrest support maybe a headrest stay having a plurality of height adjustment grooves thatare arranged in the direction of the height, or a headrest stay having aheight adjustment groove that is formed only at a specific position.

Furthermore, the height adjustment groove may be a slit formed on theside surface of the headrest stay, or may be a retaining hole forretaining the lock piece, or the like.

The lock piece needs merely to be a lock piece which has a lock nailthat is disposed at a position that faces the height adjustment grooveformed on the side surface of the headrest stay. The lock piece may be alock piece formed into a generally rectangular shape, or may be a lockpiece formed into a frame shape or a squared U shape.

The lock nail needs merely to be a lock nail that is engageable with theheight adjustment groove. The lock nail may be a lock nail protruded inthe form of a pin, or may be a lock nail formed by a peripheral edge ofthe lock piece, or the like.

The lock piece may be a lock piece that is entirely formed from the samematerial. However, if the lock piece is formed from a resin or the like,the strength of the lock nail becomes insufficient although the moldingof the engagement nail becomes easy. Furthermore, if the lock piece isformed from a metal or the like; the molding of the engagement nailbecomes difficult although a strength of the lock nail can be secured.

Therefore, the lock piece may be a lock piece in which the lock nail andthe engagement nail are formed from different materials. The lock piecemay also be formed by a metal-made plate having the lock-nail, and aresin-made knob that is provided with the engagement nail and thatallows the metal-made plate to be attached thereto.

Furthermore, if a resin-made engagement nail is integrally formed withthe resin-made knob, it is possible to adopt, for example, aconstruction in which the engagement nail has a resin arm protruded to aside opposite from the opening, and a wedge-shaped protrusion formed ona distal end side of the resin arm, and in which the engagement grooverestricts insertion of the wedge-shaped protrusion at the opening sideof the lock piece retaining hole, and forms, at a deep inward side ofthe lock-piece retaining hole, a space for receiving the wedge-shapedprotrusion so that the wedge-shaped protrusion is movable in thedirection of insertion.

When the engagement nail is inserted into the engagement groove, theinsertion of the wedge-shaped protrusion is restricted at the openingside of the lock piece retaining hole. Therefore, the wedge-shapedprotrusion is displaced to the resin arm side while bending the resinarm, as the wedge-shaped protrusion moves toward the deep inward side ofthe lock piece retaining hole.

When the wedge-shaped protrusion reaches the deep inward side of thelock piece retaining hole, the wedge-shaped protrusion can be placed inthe aforementioned spade, so that the bending of the resin arm isremoved.

Therefore, the wedge-shaped protrusion can be advanced and withdrawn inthe direction of insertion while it is received in the spaced.

Integral formation of the resin arm together with the resin-made knob ispreferable in terms of facilitation of the molding. However, the resinarm needs merely to be a resin arm that is at least capable of bendingthe wedge-shaped protrusion in a displaceable manner. The resin arm maya resin arm mounted on a member formed from a different material.

If the lockpiece retaining hole is formed to be relatively large incomparison with the dimensions of the lock piece during the resinmolding of the tube body, the lock piece tends to clatter, and itbecomes difficult to form the lock piece retaining hole in such a mannerthat the lock piece can be inserted without allowing clattering.

Therefore, it is also possible to form, in the lock piece retaininghole, a slide groove that is formed substantially parallel to thedirection of advancement and withdrawal of the lock piece and thatreceives a side end of the metal-made plate, so that the lock piece isslid along the slide groove for advancement and withdrawal in thedirection of insertion.

The slide groove may be slide grooves that are formed in opposite sidewalls of the lock piece retaining hole for receiving opposite side endsof the metal-made plate, or may be a slide groove that is formed in oneside wall of the lock piece retaining hole for receiving only one end ofthe metal-made plate.

The metal-made plate and the resin-made knob may be placed together intothe slide groove. It is also possible to construct the lock piece sothat the metal-made plate can be more easily received by the slidegroove.

For example, the metal-made plate may be formed to become wider in adirection substantially perpendicular to the direction of advancementand withdrawal of the lock piece than the resin-made knob so that themetal-made plate can be slid while it is received in the slide groove.

The metal-made plate needs merely to be a metal-made plate that has atleast a lock nail formed at a side opposite from the opening of the lockpiece retaining hole. If metal-made plates formed into a generallysquared U shape by stamping out from a metal sheet in which the recessesof squared U-shaped plate portions face each other are used, it becomespossible to reduce unwanted metal pieces that are produced during theprocess, in comparison with metal-made plates formed into a frame shape.

The tube body needs merely to be a tube body that has a retaining holecapable of retaining the headrest stay while orienting the headrest stayin the direction of the axis thereof, and a lock piece retaining holethat allows the lock piece to be inserted thereinto from a side oppositefrom the height adjustment groove and that allows the lock nail to beadvanced and withdrawn in the direction of insertion. As in the cases ofclaims 1 and claims 2, the tube body may be a tube body in which thelock piece retaining hole is formed near an opening of the retaininghole, or may be a tube body in which the lock piece retaining hole isformed in partway of the retaining hole.

The engagement structure needs merely to be an engagement structure thatengages the lock piece and the tube body with each other and restrictsmovement of the lock nail from the position of locking with the heightadjustment groove toward the opening of the lock piece retaining hole.The engagement structure may be an engagement structure that is formedat a side of the opening of the lock piece retaining hole or a sideopposite from the opening, or may be an engagement structure that isformed in the direction of height and a side face of the lock pieceretaining hole, or the like.

The engagement structure needs merely to be an engagement structure thatis constructed so as to be able to engage the tube body and the lockpiece with each other. The engagement structure may be an engagementstructure in which an engagement nail formed in the tube body is engagedwith an engagement groove formed in the lock piece, or may be anengagement structure in which, conversely, an engagement nail formed inthe lock piece is engaged with an engagement groove formed in the tubebody, or the like.

In the latter case, it is also possible to form an engagement nailprotruded from the lock piece toward a side opposite from the openingand to form an engagement groove capable of engaging with the engagementnail at the deep inward side of the lock piece retaining hole in thetube body, so that the engagement nail protruded from the lock piecetoward the side opposite from the opening is engaged with the engagementgroove formed at the deep inward side of the lock piece retaining hole.

The spring mechanism needs merely to be a spring mechanism that pressesthe lock piece in the lock piece retaining hole from the side of thelock nail to the headrest stay. The spring mechanism may be a springmechanism in which a helical coil is interposed at the opening sidebetween the lock piece and the tube body, or a spring mechanism in whicha helical coil is disposed at a side opposite from the opening betweenthe lock piece and the tube body, or the like.

The spring mechanism is not limited to a spring mechanism having ahelical coil as mentioned above, but may also be a spring mechanismconstructed by a resin-made spring structure formed integrally with thetube body, a resin-made spring structure formed integrally with the lockpiece, or the like.

A user performs height adjustment of the headrest in accordance with aneed after withdrawing the lock piece from the height adjustment groove.If the headrest is pushed down to the side of the seatback by insertingthe headrest stay deeply into the tube body, the resin-made knob becomespositioned in a narrow gap between the headrest and the seatback.

Therefore, in order to avoid engagement of the lock piece with theheight adjustment groove when the headrest is pushed down to the side ofthe seatback, a height adjustment groove is normally not formed at aposition that faces the lock piece in that situation.

Hence, as a substitute for the height adjustment groove, a tentativeengagement structure may be provided for tentatively engaging theheadrest stay with the tube body when the headrest is pushed down to theside of the seatback, so that the headrest stay is tentatively engagedwith the tube body to restrict movement of the headrest stay in thedirection of the axis thereof.

The tentative engagement herein means engagement of the headrest staywith the tube body to such a degree that in a situation where theheadrest support is installed in a vehicle, the headrest will not changein height nor clatter despite impacts caused at the time of braking orthe like, and means that when a user applies a force in such a directionas to pull the headrest stay out of the tube body in order to change theheight of the headrest, a disengaged state is established to allow aheight change.

The tentative engagement structure needs merely to be a tentativeengagement,structure that tentatively engages the headrest stay with thetube body in a situation where the headrest is pushed down to the sideof the seatback. The tentative engagement structure may be a tentativeengagement structure that is caused to tentatively engage the headreststay by an operation performed by a user, or a tentative engagementstructure that engages the headrest stay with the tube body withoutrequiring an operation performed by a user.

In the latter case, the tentative engagement structure may include atentative engagement groove formed in a side face of the headrest stay,a tentative engagement nail that tentatively engages with the tentativeengagement groove to restrict movement of the headrest stay in thedirection of the axis thereof, and a spring mechanism that urges thetentative engagement nail to a side of the tentative engagement groove.

Due to this construction, the tentative engagement nail is pressedoutwards by the side face of the headrest stay until the tentativeengagement groove reaches a position that faces the tentative engagementnail. When the tentative engagement groove reaches the position facingthe tentative engagement nail, the tentative engagement nail is moved tothe side of the tentative engagement groove by the force from the springmechanism to tentatively engage with the tentative engagement groove.

It is also possible to pre-adjust the shape of the tentative engagementnail, the spring modulus of the spring mechanism, etc. so that when itis desired that the tentative engagement nail tentatively engaged withthe tentative engagement groove be withdrawn from the tentativeengagement groove, that is, when a user is about to change the height ofthe headrest, the tentative engagement can be discontinued by the userapplying a force to pull the headrest away from the seatback, whereasthe tentative engagement is maintained despite impacts at the time ofbraking or the like. The tentative engagement structure may also beconstructed so that the tentative engagement can be discontinued by auser performing a predetermined operation, for example, depressing abutton or the like.

In this case, the tentative engagement structure may be provided with adrive mechanism that moves the tentative engagement nail to a side ofwithdrawal from the height adjustment groove.

As a result, based on depression of an operating button or the likeperformed by a user, the drive mechanism moves the tentative engagementnail to the side of withdrawal from the height adjustment groove.

The drive mechanism may be a drive mechanism that moves the tentativeengagement nail to the side of withdrawal from the height adjustmentgroove via a gear mechanism or the like, or may be a drive mechanismthat draws a metal-made tentative engagement nail by means of anelectric magnet disposed outward of the tube body, or the like.

The tentative engagement groove needs merely to be a tentativeengagement groove engageable with the tentative engagement nail. Thetentative engagement groove may be a tentative engagement groove formedin a shape different from that of the height adjustment groove, or maybe a tentative engagement groove formed in a shape identical to that ofthe height adjustment groove.

In the former case, if at the distal end side of the headrest stay, atentative engagement face formed substantially perpendicularly to thedirection of insertion into the tube body is formed in the tentativeengagement groove, the tentative engagement nail can be engaged with thetentative engagement face formed at the distal end side of the headreststay substantially perpendicularly to the direction of insertion intothe tube body when the tentative engagement nail is to be engaged withthe tentative engagement groove, so that even if force is applied insuch a direction as to pull the headrest stay out of the tube body, thetentative engagement is more likely to be maintained, and the height ofthe headrest is less likely to change.

On the other hand, in the latter case, if the tentative engagementgroove is formed by the height adjustment groove, it becomes possible toengage the lock piece and the tentative engagement nail with the heightadjustment groove in order to restrict movement of the headrest stay inthe direction of the axis thereof.

Furthermore, it is also possible to provide a constriction portion, asthe tentative engagement groove, which gradually becomes thinner fromthe distal end of the headrest stay and becomes gradually thicker towarda side of a base end thereof.

Due to this construction, as the headrest stay is inserted into the tubebody, the tentative engagement nail is pressed outwards by the distalend of the headrest stay, and is then gradually pushed back inwards inaccordance with the shape of the constriction portion to establishtentative engagement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an example of use of a headrestsupport according to an embodiment.

FIG. 2 is a perspective view showing the headrest support, into which aheadrest stay is to be inserted.

FIG. 3 is a side view showing a spring structure before a tube body isattached to a receptacle tube.

FIG. 4 is a fragmental perspective view showing an external appearanceof the receptacle tube.

FIG. 5 is a side view showing the spring structure, where the tube bodyis attached to the receptacle tube.

FIG. 6 is a front view showing a construction of a resin-made spring.

FIG. 7 is a sectional view showing the resin-made spring, where the tubebody is attached to the receptacle tube.

FIG. 8 is a sectional view showing a flexible piece before the tube bodyis attached to the receptacle tube.

FIG. 9 is a sectional view showing the flexible piece when the tube bodyis attached to the receptacle tube.

FIG. 10 is a perspective view showing a situation before a lock piece isattached to the tube body.

FIG. 11 is a plan view showing a construction of the lock piece.

FIG. 12 is a sectional view showing a situation when a metal-made platehas been engaged with a height adjustment groove.

FIG. 13 is an exploded perspective view showing a construction of a lockpiece-according to a modification.

FIG. 14 is a fragmental sectional view showing a situation before themetal-made plate is attached to a resin-made knob.

FIG. 15 is a fragmental sectional view showing a situation when themetal-made plate has been attached to the resin-made knob.

FIG. 16 is a plan view showing a construction of the lock piece n whichthe metal-made plate has been attached to the resin-made knob.

FIG. 17 is a fragmental sectional view showing a shape of an engagementgroove according to a modification.

FIG. 18 is a perspective view showing a state before a metal-made plateaccording to the modification is attached to the resin-made knob.

FIG. 19 is a perspective view showing a state after the metal-made platehas: been attached to the resin-made knob.

FIG. 20 is a sectional view showing an internal construction of theheadrest support.

FIG. 21 is a front view showing a construction of a lock piece where awidened metal-made plate is applied.

FIG. 22 is a front view showing a construction a lockpiece where ametal-made plate having a width equal to that of the resin-made knob isapplied.

FIG. 23 is a sectional view showing a state during insertion of the lockpiece into a lock piece retaining hole.

FIG. 24 is a sectional view showing a position of the lock piece duringa normal state.

FIG. 25 is a sectional view showing a position of the lock piece when anoperating portion is pressed.

FIG. 26 is a sectional view showing a state before a lock pieceaccording to a modification is inserted into a lock piece retaininghole.

FIG. 27 is a sectional view showing a state after the lock piece hasbeen inserted in the lock piece retaining hole.

FIG. 28 is a sectional view showing a state before a lock pieceaccording to another modification is inserted into a lock pieceretaining hole.

FIG. 29 is a sectional view showing a state after the lock piece hasbeen inserted in the lock piece retaining hole.

FIG. 30 is a perspective view showing a situation when the headrest hasbeen pushed down to a side of a seatback.

FIG. 31 is a plan view showing a headrest stay with a tentativeengagement groove formed thereon.

FIG. 32 is a plan view showing a headrest stay wherein height adjustmentgrooves and a tentative engagement groove are formed in the same shape.

FIG. 33 is a plan view showing a headrest stay with a tentativeengagement formed at a base end side.

FIG. 34 is a perspective view showing a construction of a headrestsupport according to a conventional art.

BEST MODES FOR CARRYING OUT THE INVENTION

Embodiments of the invention will be described hereinafter withreference to the drawings.

FIG. 1 shows an example of use of a headrest support according to afirst embodiment of the invention in a perspective view.

In the drawing, a frame 11 aligned in an upper side portion of aseatback 10 in a direction of a width thereof is provided withreceptacle tubes 12, 13 that are aligned in a direction of alongitudinal dimension of the seatback 10 and that are fixed by weldingat a predetermined interval.

Headrest stays 21, 22 protruded downward from a bottom surface of aheadrest 20 are inserted into resin-made tubular headrest supports 30,40 that are inserted in and supported by the receptacle tubes 12, 13.The headrest stays 21, 22 are indirectly supported by the frame 11 viathe headrest supports 30, 40.

One of the juxtaposed headrest stays 21, 22, that is, a headrest stay21, has a plurality of height adjustment grooves 21 b that are arrangedin a side surface of the headrest stay 21 extending from a distal endside thereof. As shown in FIG. 2, a headrest support 30 into which theheadrest stay 2 is inserted is made up of a tube body 31 formingsubstantially the whole body of the headrest support 30, and a lockpiece 32 that is supported at an upper end of the tube body 31 and thatis engageable with the height adjustment grooves 21 b. It is assumedthat in FIG. 2, a left-upward side in the sheet of drawing is defined asa left side, and an upward side in the sheet of drawing is defined as anupper side.

As shown in FIG. 3, at a n upper end side of the tube body 31, a springstructure 33 a is formed substantially vertically downward from a lowerside of an opening of a lock piece retaining hole 31 b (see FIG. 10) forinsertion of the lock piece 32.

The spring structure 33 a is protruded from a lower side of the lockpiece retaining hole 31 b, and has at its distal end side a ring portion33 a 1 that is deformable in a substantially vertical direction.Flexible pieces 34, 34 shown in FIG. 2 that are provided in a lowerportion of the tube body 31 are bent inwards while the tube body 31 isbeing inserted into the receptacle tube 12. When the insertion of thetube body 31 into the receptacle tube 12 is completed as the flexiblepieces 34, 34 protrude from a lower end opening of the receptacle tube12, and are forced outwards by their own springy forces so as to engagewith an opening end portion of the receptacle tube 12, the ring portion33 a 1 is pressed against a peripheral edge of an opening of thereceptacle tube 12, thereby urging an upper end side of the headrestsupport 30 upwards from the side of the receptacle tube 12.

Therefore, if an impact occur in an up-down direction, the impact can beabsorbed by the ring portion 33 a 1 deforming, that is, crushing, in theup-down direction.

At such a moment, the spring structure 33 a absorbs the impact whiledispersing it at two side end sites of the ring portion 33 a 1.Therefore, the impact can be efficiently absorbed, and damages to thespring structure 33 a can be reduced.

As shown in FIG. 4, a back face side of the tube body 31 shown in FIGS.1 and 2 is provided with a stopper nail 33 b protruded substantiallyvertically downwards from an upper end side. As shown in FIG. 5, thereceptacle tube 12 has a cutout groove 12 a that extends substantiallyin a direction of an axis of the receptacle tube 12 from an opening endportion thereof and that is capable of receiving the stopper nail 33 b.

Owing to this construction, the stopper nail 33 b is inserted into thecutout groove 12 a as shown in FIG. 6 when the tube body 31 is insertedinto the receptacle tube 12. Thus, rotation of the tube body 31 relativeto the receptacle tube 12 in circumferential directions is restricted.

The cutout grooves 12 a, 13 a formed in the receptacle tubes 12, 13 areformed at positions that are offset toward sides that are remote fromeach other as indicated in FIG. 5, so that the headrest supports 30, 40are received by the predetermined receptacle tubes 12, 13.

This construction prevents reversed insertion of the headrest support 30provided with the lock piece 32 and the headrest support 40 not providedwith a lock piece 32.

As shown in FIGS. 3 and 4, resin-made springs 35 are formed on the tubebody 31 in order to prevent clattering even when the headrest support 30inserted in the receptacle tube 12 receives an impact in a right-leftdirection.

The resin-made springs 35 have flexible portions 35 a that are formedbetween cutout grooves extending in the outer peripheral surface of thetube body 31 substantially parallel to each other in up-down directionsand that has flexibility substantially in directions of the diameter ofthe tube body 31. Protrusions 35 b are protruded outwards from theflexible portions 35 a.

Due to this construction, when the tube body 31 is inserted. in thereceptacle tube 12, the protrusions 35 b press an inner peripheralsurface of the receptacle tube 12 while causing the flexible portions 35a to bend inwards as shown in FIG. 7, thereby preventing the tube body31 from clattering.

Furthermore, in order to prevent clattering even when the headrestsupport 30 inserted in the receptacle tube 12 receives an impact in afront-rear direction, a clattering preventative structure 36 is formedat positions in the front-rear direction near the upper end side andnear a central portion of the tube body 31.

The clattering preventative structure 36 has generally rectangularflexible pieces 36 a that are formed by a generally squared U-shapedgroove being formed in the outer peripheral surface of the tube body 31.A distal end side of each flexible piece 36 a is slightly protrudedoutwards as shown in FIG. 8 before the tube body 31 is inserted into thereceptacle tube 12.

When the tube body 31 is inserted into the receptacle tube 12, theflexible pieces 36 a are pressed and therefore bent inwards by the innerperipheral surface, so that sectional shapes of the tube body 31 arechanged into generally ring-like sectional shapes as shown in FIG. 9.

In this situation, the flexible pieces 36 a tend to restore theiroriginal shape and therefore press the inner peripheral surface of thereceptacle tube 12, so that the tube body 31 can be prevented fromclattering.

Each-flexible piece 36 a has a tapered shape that gradually becomesthinner toward a lower end so as to facilitate insertion of the tubebody 31 into the receptacle tube 12 even if the flexible piece 36 ainterferes with an opening edge portion of the receptacle tube 12 whenthe tube body 31 is inserted into the receptacle tube 12 from the upperend opening.

The spring structure 33 a, the stopper nail 33 b, the resin-made springs35 and the clattering preventative structure 36 are described above inconjunction with the tube body 31. Comparable structures are formed atcorresponding position in a tube body constituting the headrest support40.

As shown in FIG. 10, the tube body 31 has a through-hole 31 a extendingthrough in the up-down direction, and has, at is upper end, the lockpiece retaining hole 31 b having an opening directed rightwards.Therefore, the tube body 31 retains the headrest stay 21 inserted intothe through-hole 31 a, and supports the lock piece 32 inserted into thelock piece retaining hole 31 b from the right side.

The lock piece 32 has a generally rectangular metallic plate 32 aengageable with the height adjustment grooves 21 a, and a resin-madeknob 32 b that is capable of being inserted into the lock pieceretaining hole 31 b while carrying thereon the metal-made plate 32 a.When the headrest stay 21 is inserted into the through-hole 31 a asindicated in FIG. 2 after the metal-made plate 32 a attached to theresin-made knob 32 b is inserted into the lock piece retaining hole 31b, the metal-made plate 32 a engages with a height adjustment groove 21a to fix the height of the headrest 20. In this sense, the metal-madeplate 32 a forms a lock nail that is referred to in the invention. Asshown in FIG. 11, the resin-made knob 32 b has a frame portion 32 b 1that has a through-hole to avoid interference with the headrest stay 21,an operating portion 32 b 2 formed integrally at a right-side end of theframe portion 32 b 1, and a flexible arm 32 b 3 protruded leftwards fromthe frame portion 32 b 1. After the metal-made plate 32 a is placedbetween four protrusions 32 b 4 protruded upward from an upper surfaceof a left side portion of the frame portion 32 b 1, the lock piece 32 isinserted into the lock piece retaining hole 31 b by pushing theoperating portion 32 b 2 leftwards while disposing a spring 32 c betweenthe lock piece 32 and the opening side of the lock piece retaining hole31 b, as indicated in FIG. 10.

As shown in FIG. 12, a wedge-shaped protrusion 32 b 5 is formed on adistal end side of the flexible arm 32 b 3. An engagement groove 31 ccapable of receiving and engaging with the wedge-shaped protrusion 32 b5 is formed deeply inwards within the lock piece retaining hole 31 b.Therefore, when the wedge-shaped protrusion 32 b 5 reaches theengagement groove 31 c after the wedge-shaped protrusion 32 b 5 isinserted deeper into the lock piece retaining hole 31 b while being bentupward, the wedge-shaped protrusion 32 b 5 is forced back down to engagewith the engagement groove 31 c, so that the lock piece 32 cannot bepulled out of the opening of the lock piece retaining hole 31 b. In thissense, the engagement groove 31 c and the wedge-shaped protrusion 32 b 5form an engagement mechanism referred to in the invention.

When the headrest stay 21 is inserted from the through-hole 31 a asindicated in FIG. 2, an inwardly located edge portion of the lock piece32 is received by a height adjustment groove 21 a and thus establishesan engaged state since the lock piece 32 is urged toward the openingside of the lock piece retaining hole 31 b by the spring 32 c as shownin FIG. 12. In this sense, the spring 32 c forms a spring mechanismreferred to in the invention.

As shown in the drawing, the engagement groove 31 c extends from adeeply inward portion of the lock piece retaining hole 31 b to a sideopposite from the opening of the lock piece retaining hole 31 b, so thatthe wedge-shaped protrusion 32 b 5 inserted therein can be moved in thedirection of insertion.

Therefore, when a user pushes the operating portion 32 b 2 toward adeeply inward portion of the lock piece retaining hole 31 b, the lockpiece 32 is moved further inwards in the lock piece retaining hole 31 bagainst the force from the spring 32 c, so that the metal-made plate 32a is withdrawn from the height adjustment groove 21 a.

Then, the headrest stay 21 enters a state of being advanceable andwithdrawable in the directions of an axis thereof. Therefore, the userchanges the height of the headrest 20 to a desired height, and movesanother height adjustment groove 21 a to a position that faces themetal-made plate 32 a, and then releases the operating portion 32 b 2,so that the lock piece 32 is moved back toward the opening of the lockpiece retaining hole 31 b by the force from the spring 32 c and themetal-made plate 32 a is received in and engaged with the heightadjustment groove 21 a.

As shown in FIG. 13, the lock piece 32 may have a pair of stopper pieces32 b 6 that are provided integrally with and protruded upwards from theupper surface of the left side portion of the frame portion 32 b 1, andthe metal-made plate 32 a may have stopper holes 32 a 1 at positionsthat face the stopper pieces 32 b 6, so as to prevent the metal-madeplate 32 a from clattering against the resin-made knob 32 b.

More specifically, as shown in FIG. 14, each of the stopper pieces 32 b6 is formed,by a pair of semi-cylindrical bodies that have flexibilityinwards in directions of a diameter thereof, and that are disposedleaving a predetermined interval therebetween. As shown in FIG. 15, eachstopper piece 32 b 6 is inserted into the stopper hole 32 a 1 while thestopper piece 32 b 6 is pressed inwardly in the directions of thediameter by a peripheral wall surface of the stopper piece 32 a 1. Thus,the metal-made plate 32 a is attached to the resin-made knob 32 b asshown in FIG. 16.

The stopper pieces 32 b 6 inserted in the stopper holes 32 a 1 tend torestore the original posture and therefore press the peripheral wallsurfaces of the stopper holes 32 a 1. Therefore, the metal-made plate 32a can be prevented from clattering due to the force of engagementbetween the stopper pieces 32 b 6 and the stopper holes 32 a 1.

In this embodiment, the engagement groove 31 c penetrates from thedeeply inward portion of the lock piece retaining hole 31 b to a side,as shown in FIG. 12. However, the engagement groove 31 c needs merely tostop at least the wedge-shaped protrusion 32 b 5 formed on theresin-made knob 32 b and receive the wedge-shaped protrusion 32 b 5 sothat the wedge-shaped protrusion 32 b 5 can be moved in substantiallyhorizontal directions. As shown in FIG. 17, an engagement groove 31 cmay penetrate downward, so that the opening of the engagement groove 31c is formed at a location that is hard to be seen by a user.

Furthermore, the metal-made plate 32 a having a generally rectangularshape is attached to the resin-made knob 32 b in order to reduce theamount of metal plates used. However, a requirement is merely to securea lock portion that is receivable in and engageable with the heightadjustment grooves 21 a. For example, it is also possible to use ametal-made plate having a frame shape, an L-like shape, a squared letter“U” shape, etc.

A case where the metal-made plate 32 a has a frame shape will bedescribed with reference to FIGS. 18 to 25.

As shown in FIGS. 18 and 19, a metal-made plate 50 is formed by a framebody that has a through-hole to avoid interference with the headreststay 21 and that has a width greater than that of the resin-made knob 32b. The metal-made plate 50 has mounting pieces 50 a, 50 a that areprotruded leftwards from a left side surface of the metal-made plate 50.

The metal-made plate 50 locks the headrest stay 21 by engaging aright-side edge portion 50 b of the through-hole with a desired heightadjustment groove 21 a.

On the other hand, the resin-made knob 32 b has a frame portion 32 b 1that has a through-hole as in the metal-made plate 50, and an operatingportion 32 b 2 that is integrally formed on a left side end of the frameportion 32 b 1. A right-side wall face of the operating portion 32 b 2has mounting holes 32 b 7, 32 b 7 in which the mounting pieces 50 a, 50a can be inserted. Two right-side corners of the frame portion 32 b 1are provided with stopper pieces 32 b 8, 32 b 8 protruded upwards.

Due to this construction, the metal-made plate 50 is attached to theresin-made knob 32 b by engaging right-side ends of the metal-made plate50 with the stopper pieces 32 b 8, 32 b 8 from a left side whileinserting the mounting pieces 50 a, 50 a into the mounting holes 32 b 7,32 b 7.

Then, as shown in FIG. 20, the lock piece is inserted deeply into thelock piece retaining hole 31 b, with side end portions of the metal-madeplate 50 being received by slide grooves 31 b 1, 31 b 1 that are formedhorizontally in two side walls of the lock piece retaining hole 31 b.

In this case, the metal-made plate 50 having an increased width isattached to the resin-made knob 32 b, and the side end portions of themetal-made plate 50 are guided by the slide grooves 31 b 1, 31 b 1, asshown in FIG. 21. However, it is not necessary to increase the width ofthe metal-made plate 50 alone for the guiding operation. It is alsopossible to provide the metal-made plate 50 and the resin-made knob 32 bwith equal widths as shown in FIG. 22 so that the lock piece 32 isguided by the entire lock piece retaining hole 31 b.

As in the foregoing embodiment, an engagement structure is formedbetween the tube body 31 and the lock piece 32 in order to restrict themovable range of the lock piece 32 and prevent the lock piece 32 fromfalling apart from the tube body 31 when the lock piece 32 isinserted-in the lock piece retaining hole 31 b.

The lock piece retaining hole 31 b has a vertical width that isapproximately equal to a sum of the thickness of the metal-made plate 50and the thickness of the frame portion 32 b 1.

Due to this construction, when the wedge-shaped protrusion 32 b 5 isdirected toward the opening of the lock piece retaining hole 31 b andthe lock piece 32 is inserted into the lock piece retaining hole 31 b, aright-side end of the wedge-shaped protrusion 32 b 5 interferes with theopening of the lock piece retaining hole 31 b.

Then, as shown in FIG. 23, the flexible arm 32 b 3 is bent so as todisplace the wedge-shaped protrusion 32 b 5 upwards as the lock piece 32is inserted deeply into the lock piece retaining hole 31 b.

When the lock piece 32 is inserted further deeply into the lock pieceretaining hole 31 b so that the wedge-shaped protrusion 32 b 5 reachesthe engagement groove 31 c, the wedge-shaped protrusion 32 b 5 isreceived by the engagement groove 31 c and the bending of the flexiblearm 32 b 3 is removed, as shown in FIG. 24.

If an attempt is made to pull the lock piece 32 leftwards from the lockpiece retaining hole 31 b, the wedge-shaped protrusion 32 b 5 contactsthe engagement groove 31 c, so that the movement of the wedge-shapedprotrusion 32 b 5 to the left is restricted and the lock piece 32continues to be retained by the lock piece retaining hole 31 b. Thus,the lock piece 32 is prevented from falling apart from the tube body 31.

As shown in the drawing, since the lock piece 32 is inserted in the lockpiece retaining hole 31 b with the spring 32 c disposed between aright-side wall surface of the operating portion 32 b 2 and the openingof the lock piece retaining hole 31 b, the lock piece 32 is urgedleftwards. Therefore, normally, the wedge-shaped protrusion 32 b 5 ispressed against a left-side wall surface of the engagement groove 31 cwhen the wedge-shaped protrusion 32 b 5 is retained within the tube body31.

Therefore, if in this situation, a height adjustment groove 21 a isadjusted to the position that faces the right-side edge portion 50 b ofthe metal-made plate 50, the right-side edge portion 50 b engages withthe height adjustment groove 21 a, thereby locking the headrest stay 21.

If a user presses the operating portion 32 b 2 rightwards, thewedge-shaped protrusion 32 b 5 is moved rightwards within the engagementgroove 31 c as shown in FIG. 25, so that the right-side edge portion 32a 2 withdraws from the height adjustment groove 21 a and the headreststay 21 becomes movable up and down.

When the operating portion 32 b 2 is released, the lock piece 32 isreturned leftwards until the wedge-shaped protrusion 32 b 5 contacts theleft-side wall surface of the engagement groove 31 c, due to the spring32 c urging the lock piece 32 leftwards.

As a result, the right-side edge portion 50 b engages with the heightadjustment groove 21 a again as shown in FIG. 24, thereby locking theheadrest stay 21 with the tube body 31

Although in the foregoing description, the flexible arm 32 b 3 and thewedge-shaped protrusion 32 b 5 are formed on the side of the resin-madeknob 32 b, and the engagement groove 31 c is formed on the side of thetube body 31, this construction is merely an example of the engagementstructure. It is also possible to form a flexible arm 60 and awedge-shaped protrusion 61 on the side of the tube body 31 and to forman engagement groove 62 on the side of the resin-made knob 32 b as shownin FIG. 26.

Due to this construction, when the lock piece 32 is inserted into thelock piece retaining hole 31 b, a left-side end of the wedge-shapedprotrusion 61 interferes with a right-side end of the resin-made knob 32b.

Then, the resin-made knob 32 b moves over the wedge-shaped protrusion61, with the flexible arm 60 being bent. The wedge-shaped protrusion 61is subsequently received in the engagement groove 62 as shown in FIG.27.

Therefore, even if an attempt is made to pull the lock piece 32leftwards out of the lock piece retaining hole 31 b, leftward movementof the wedge-shaped protrusion 61 is restricted.

Furthermore, it is also possible to form a flexible arm 70 and awedge-shaped protrusion 71 formed at the side of the opening of the lockpiece retaining hole 31 b and to form an engagement groove 72 on theside of the operating portion 32 b 2 formed on the resin-made knob 32 bas shown in FIG. 28 so that the wedge-shaped protrusion 71 and theengagement groove 72 can be engaged as shown in FIG. 29.

Although the engagement structure has been described in conjunction withthe metal-made plate 50, it is also possible to apply the metal-madeplate 32 a of the embodiment in a similar manner.

If the headrest 20 is too high for a user, the headrest 20 must bepushed down toward the seatback 10 for use as shown. in FIG. 30.

In this case, the operating portion 32 b 2, which is pressed in order tochange the height of the headrest 20, is positioned in a narrow gapformed between the headrest 20 and the seatback 10.

Therefore, no height adjustment groove 21 a is formed at a position thatfaces the metal-made plate 32 a in this situation so that the height ofthe headrest 20 can be changed even if a user's finger cannot reach theoperating portion 32 b 2 when the height is to be changed.

However, if there is no structure for restricting movement of theheadrest stay 21 in the directions of the axis thereof when the headrest20 is used at a position where the headrest 20 is pushed down to theside of the seatback 10, the seatback 10 may move up and down and maychange in height, for example, when a driver performs braking.Therefore, besides the engagement structure formed by the metal-madeplate 32 a and the height adjustment groove 21 a, it is also possible toprovide a tentative engagement structure for restricting movement of theheadrest stay 21 in the directions of the axis thereof only when theheadrest 20 is used at the position where the headrest 20 is pushed downto the side of the seatback 10.

As shown in FIG. 31, this tentative engagement structure is made up of atentative engagement groove 21 b formed below the height adjustmentgrooves 21 a arranged on the headrest stay 21, and a not-shown tentativeengagement portion that is formed on a peripheral surface of the tubebody 31. When the headrest stay 21 is inserted deeply into the tube body31 so that the lower end of the headrest 20 is pressed against the upperend of the tube body 31, the tentative engagement portion tentativelyengages with the tentative engagement groove 21 b, thereby locking theheadrest stay 21 and restricting up-down movements thereof.

As shown in the drawing, each height adjustment groove 21 a has an uppersurface that is formed substantially horizontally, so that when engagedwith the metal-made plate 32 a, the height adjustment groove 21 arestricts downward movement of the headrest stay 21. On the other hand,the tentative engagement groove 21 b has a lower surface that is formedsubstantially horizontally, so that when engaged with the tentativeengagement portion, the tentative engagement groove 21 b restrictsupward movement of the headrest stay 21.

The tentative engagement structure is designed so that upward movementof the headrest stay 21 is restricted if there occurs force of amagnitude that is approximately equal to or less than forces applied tothe vehicle at the time of braking or the like, and so that when a userapplies a force to pull up the headrest 20, the tentative engagementgroove 21 b is guided upwards to allow a change in the height of theheadrest 20.

Furthermore, as shown in FIG. 32, it is also possible to eliminate thedifferences between the height adjustment grooves 21 a and the tentativeengagement groove 21 b so that all the grooves formed in the sidesurface of the headrest stay 21 have identical shapes.

The shape of the grooves shown in the drawing is a mere example, and isnot restrictive. It is also possible to form a tentative engagementgroove so as to have a shape identical to the shape of the heightadjustment grooves 21 a shown in FIG. 31. It is also possible to formheight adjustment grooves so as to have a shape identical to that of thetentative engagement groove 21 b shown in the drawing.

Furthermore, in this embodiment, the tentative engagement portion formedseparately from the metal-made plate 32 a of the lock piece 32 is usedfor the tentative engagement. However, as shown in FIG. 33, it is alsopossible to form a tentative engagement groove 21 b at a base end sideof the headrest stay 21 and to tentatively engage the tentativeengagement groove 21 b with the metal-made plate 32 a.

That is, if the shape of the tentative engagement groove 21 b is setsuch that upward movement of the headrest stay 21 is restricted if thereoccurs force of a magnitude that is approximately equal to or less thanforces applied to the vehicle at the time of braking or the like, andsuch that when a user applies a force to pull up the headrest 20, thetentatively engaged state is discontinued to allow a change in theheight of the headrest 20, it is possible to cause the lock piece 32 tofunction as a tentative engagement structure similarly to the engagementportion.

Thus, it becomes possible to provide a headrest support 30 that absorbsimpact occurring on the headrest 20 in the direction of height thereofby means of the spring structure 33 a formed vertically downward from alower side of the lock piece retaining hole 31 b, and that prevents theclattering of the tube body 31 relative to the receptacle tube 12 whilehaving sufficient strength by means of the resin-made springs 35 formedbetween the cutout grooves extending in the outer peripheral surface ofthe tube body 31 substantially parallel in the up-down direction, andthat can easily be assembled by the lock piece 32, the tube body 31 andthe spring 32 c.

Industrial Applicability

As described above, the invention is able to provide a headrest supportcapable of absorbing impact occurring to the headrest in the directionof the height.

Furthermore, according to the invention in accordance with claim 2, itis possible to provide a headrest support capable of preventing theclattering of the tube body relative to the receptacle tube by using aresin-made spring that has sufficient strength.

Still further, according to the invention in accordance with claim 3, itis possible to provide a headrest support that allows an improvement inassembly workability.

What is claimed is:
 1. A headrest support comprising: a tube body thatis inserted into and supported by a receptacle tube disposed in aseatback, and that retains a headrest stay inserted therein, and thatallows an adjustment of a height of the headrest stay; and a springstructure that is protruded from a distal end side of the tube bodytoward an opening end portion of the receptacle tube, and that urges thedistal end side of the tube body to move away from the opening endportion of the receptacle tube when the tube body is pushed down to aside of the receptacle tube, wherein said spring structure includes aring portion that is deformable in a substantially vertical direction,and said spring structure is disposed below a lock piece retaining holeof the tube body that receives a lock piece for engaging with theheadrest stay.
 2. A headrest support comprising: a tube body that isinserted into and supported by a receptacle tube disposed in a seatback,and that retains a headrest stay inserted therein, and that allows anadjustment of a height of the headrest stay; and a resin-made springincluding a flexible portion that is formed between cutout groovesextending in an outer peripheral surface of the tube body substantiallyparallel in a direction of an axis of the tube body, and that has aflexibility substantially in a direction of a diameter of the tube body,and a protrusion that is protruded outwards from the flexible portion,and that presses an inner peripheral surface of the receptacle tubewhile bending the flexible portion inwards when the tube body isinserted in the receptacle tube.
 3. A headrest support comprising: alock piece having a lock nail disposed at a position that faces a heightadjustment groove formed on a side face of a headrest stay; a tube bodyhaving a retaining hole capable of retaining the headrest stay whileorienting the headrest stay in a direction of an axis thereof, and alock piece retaining hole that allows the lock piece to be insertedthereinto from a side opposite from the height adjustment groove, andthat allows the lock nail to be advanced and withdrawn in a direction ofinsertion; an engagement structure that engages the lock piece and thetube body with each other and restricts a movement of the lock nail froma position of locking with the height adjustment groove toward anopening of the lock piece retaining hole; and a spring structure thatpresses the lock piece disposed in the lock piece retaining hole from aside of the lock nail to the headrest stay, wherein the engagementstructure includes a flexible arm disposed on the lock nail, having awedge shaped protrusion at an end thereof, and wherein the lock pieceretaining hole has an engagement groove for receiving the wedge shapedprotrusion of the lock nail, and wherein the lock piece includes a frameportion and a metal plate disposed on the frame portion, and the frameportion has a protrusion that engages with a hole of the metal plate.